Method and apparatus for producing gaseous products from solid fuel and using same for the reduction of iron ore



E. G. BAILEY Aug. 31, 1965 METHOD AND APPARATUS FOR PRODUCING GASEOUSPRODUCTS FROM SOLID FUEL AND USING SAME FOR THE REDUCTION OF IRON OREFiled Oct. 10, 1960 4 Sheets-Sheet l g- 1965 G. BAILEY METHOD ANDAPPARATUS FOR PRODUCING GASEOUS PRODUCTS FROM SOLID FUEL AND USING SAMEFOR THE REDUCTION OF IRON ORE Filed Oct. 10, 1960 4 Sheets-Sheet 2 Aug.31, 1965 E. G. BAILEY 3,203,784

METHOD AND APPARATUS FOR PRODUCING GASEOUS PRODUCTS FROM SOLID FUEL ANDUSING SAME FOR THE REDUCTION OF IRON ORE Filed Oct. 10, 1960 4Sheets-Sheet s 1, 1965 E. G. BAILEY 3,203,784

METHOD AND APPARATUS FOR PRODUCING GASEOUS PRODUCTS FROM SOLID FUEL ANDUSING SAME FOR THE REDUCTION OF IRON ORE Filed Oct. 10, 1960 4Sheets-Sheet 4 United States Patent 3,203,784 METHOD AND APPARATUS FORPRODUCING GA'SEOUS PRODUCTS FROM SOLID FUEL AND g sgro SAME FOR THEREDUCTION OF IRON Ervin G. Bailey, Easton, Pa., assignor to BaileyInventions, Inc., Easton, Pa., a corporation of Pennsylvania Filed Oct.10, 1960, Ser. No. 61,633 '2 Claims. (Cl. 7540) This is acontinuation-in-part of application S.N. 817,143, filed June 1, 1959 andnow abandoned.

This invention relates to the production of clean carbon monoxide gas bythe gasification of solid carbon-containing fuel for reactive agent orthermal purposes, for example, in a chemical reduction process, as inthe reduction of iron ore, or in the production of high-temperaturecarbon-monoxideor carbon-dioxide-containing gases for a variety ofthermal uses.

Broadly, the invention is based upon the principle of burning avertically descending charge of solid organic fuel in such configurationand in such manner as to insure that the major gaseous reaction productsformed in the bed emerge from a surface of the bed other than thefuel-replenishing surface thereof. To this end, the descending fuel bedis supported at one side by a porous vertically-extending refractoryretaining wall. The opposite side of the bed constitutes the off-gassurface and is defined, supported and retained in substantially verticalposition in juxtaposition With an adjacent vertically descending bodycontaining a solid inorganic liquefiable material, chosen for itsvertical flow characteristics at the operating temperature. Separateintermittent or continuous feeds of the properly chosen inorganicmaterial and organic fuel onto the top surfaces of the descendingcharges are so controlled that the interface therebetween can besubstantially parallel to the rear refractory wall whereby a fuel bed ofsubstantially constant and predetermined thickness is continuouslymaintained. Combustionsupporting gas such as air, oxygen oroxygen-enriched air may then be fed through the rear Wall at suitabletemperature and through the descending bed of fuel directly into theadjacent descending bed of inorganic material, and the composition andvolume of the gas and the thickness of the fuel bed are controlled tocause, as desired, only incomplete oxidation of carbon in the solid fuelto carbon monoxide or to secure more complete combustion to carbondioxide, or a combination of the two.

Because the off-gas surface of the fuel bed is covered by the juxtaposeddescending liquefiable material, such off-gas interface as well as theinterior of the bed, along most of its height, may be maintained, whendesired, at a temperature exceeding the liquid flowing point of thenon-combustibles contained in the solid fuel and hence thesenoncombustibles, which at such temperatures are either themselves moltenor part of a flowable eutectic, tend to drain downwardly through thefuel bed in liquid form and are thus gravity separated from the gaseousstream flowing transversely through the descending bed. This descendingflow also acts in the manner of a gas washer to minimize unburned fuelparticles proceeding with the gaseous reaction products produced in thefuel bed into the inorganic material.

In some cases, supplemental heat input may be provided to the beds fromelectrodes or from other strategically disposed subsidiary orsupplemental solid fuel feeds.

3,203,734 Patented Aug. 31, 1965 In other cases, steam may be introducedto limit the upper temperature developed in the bed.

The thickness of the retaining bed which is usually substantially freefrom fuel, affects the temperature of the gases released at the off-gassurface of the inroganic material and is controlled according to thenature or temperature or both, of the off gases desired.

Appying the principles of the invention to iron ore reduction, forexample, great advantages accrue from using as the sustaining verticallydescending charge, iron oxide ore which according to one preferredmethod of operation, is not intermixed with solid carbon fuel such asthe coke used in the present blast furnace operation; for the thicknessof the fuel bed is controlled to insure that sufficient carbon monoxidegas emerges from the fuel bed to reduce the ore contained in theretaining bed charge without the necessary generation of further carbonmonoxide gas within the ore zone from non-ore sources. The entire solidfuel requirement for performing the iron ore reduction originates withinthe fuel bed outside of the ore bed.

Absence of fuel carbon in the reducing Zone of the iron ore avoids theless predictable complicated endothermic reactions which take place innormal blast furnace operation. It tends to avoid loss of reducing gaswhich is not put to effective reactive use before escape. In accordancewith the preferred form of iron oxide reduction, it is possible tooperate with a much more nearly complete combustion in the ore zone ofthe carbon monoxide to carbon dioxide with the oxygen obtained from thereduction of 2Fe O to 4FE+3O before the gaseous flow reaches the off-gassurface of the iron oxide bed.

These and other objects of the invention will be more readily understoodwhen taken in connection with the description of the accompanyingdrawings wherein:

FIG. 1 is a vertical cross-section through an iron reduction furnacedesigned for operation in accordance with this invention, being brokenaway to indicate extent;

FIG. 2 is a plan view, partly in cross-section, also broken away toindicate extent, of the furnace, taken along the line 22 of FIG. 1;

FIG. 3 is a cross-sectional View taken along the line 33 of FIG. 1;

FIG. 4 is a vertical cross-section of a modified form of furnace;

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 4;

FIG. 6 is a vertical cross-section through a still further modified formof iron reduction furnace;

FIG. 1 shows a furnace comprising a refractory hearth 18. An upstandingrefractory wall 19 merges into an inclined imperforate refractorysupporting surface 20. The back of the apparatus includes a furtherupstanding refractory wall 40 communicating with a plenum chamber 42which is connected to a source of combustionsupporting gas such aspre-heated air, oxygen-enriched air, or oxygen, supplemented if desiredby a steam inlet or a gas fuel inlet. A series of adjustable baffles 44aid in directing the combustion-supporting gases into uniform, orotherwise distributed flow along the height of the wall through spacedapertures 45, provided by spacing refractory bricks.

Arranged over the furnace chamber are two feeds 50 and 51, one for fueland one for ore, each provided with a conventional screw feed mechanismfor distributing the material in a continuous manner across the width ofthe furnace. The first feed 50 is located over the rear portion of thefurnace and the second feed 51, is at the top of a casing 63 havingdownwardly diverging walls 66 and 68.

Above the feed 51 is a stack 52 for the off gases.

A supplemental combustion-supporting gas inlet 53 is positioned abovethe fuel feed 59 and an adjustable pivoted gate 55 is provided justbelow the fuel feed 59 in order to control the thickness of the fuelbed. The gate 55 will have to be water-cooled (not shown), and it shouldbe understood that water-cooled screen tubes or other water-cooledstructure may be utilized in partial or entire replacement of therefractory walls, as needed, both in FIG. 1 and in the other embodimentsof the invention subsequently described.

The apparatus may also contain electrodes 64 along the upper portion ofthe walls 66 and 68 and supplemental air inlets 61 for introduction ofair or gaseous fuel if required.

In operation any free-burning solid fuel may be fed at the feed 50 whileessentially ore and proper proportions of limestone may be fed at theother feed 51. By properly controlling the two feeds, an interface ismaintained by the juxtaposition of the beds of different content, thusmaintaining an organic fuel bed of substantially uniform thickness andcomprising a Zone I of sufficient thickness to foreclose completecombustion of the carbon with the result that the gases emerging at theinterface into Zone II are substantially entirely carbon monoxide orCO+H in case steam is used for limiting the temperature of the fuel bed.

The result is that hot gases, i.e., above 1500 F., and preferably above2700" F., proceed across the interface into reduction Zone II in suchvolume as to reduce the iron ore with conversion of the carbon monoxideinto carbon dioxide.

The reduction zone is very simple with only the ore, stone, and slagflowing downwardly from Zone III, where the charge is fully preheated bythe rising gases which by heat exchange to the incoming ore are cooledto less than 300 F., and in Zone II the counterflow of hot gas, rich incarbon monoxide and possibly H completes the reduction of the FeO to Fe.The gas continues its upward flow as in the standard blast furnace wherethe remaining carbon monoxide and H reduce the E2 and Fe O to FeOeffectively in a diminishing percentage of reduction gas, until it ispractically all converted to C0 and H 0. All of the oxygen needed issupplied from the 0 from the reducing of the ore, and its combinationwith CO and H supplies the required amount of heat to make thereduction.

There need be much less CO or H escape unburned as is inevitable withthe standard blast furnace where the fuel is fed in with the charge atthe top of the furnace, and much is wasted from the loss of CO and Hproduced in a zone where they cannot possibly be used before escape.

The rate at which ore is supplied in the present process is proportionedto the supply of reducing gases, CO and H as indicated by gastemperatures and gas analyses at the proper points.

When using solid fuel with air as the oxidant, either the fuel or theair, or both, may be pre-heated. Air at 280 F. will burn some carbon toCO to provide the required temperature in Zone I. The air can bepre-heated to 1300 F. or higher, as cost permits.

The charge of ore and stone must be adequately heated and calcinedbefore entering the final stage of the reducing zone, as there is aclose balance between the heat required for reduction of ore and thatmade available from the combustion of CO and H using the 0 released fromthe ore by the reduction.

If the sensible heat in the gas leaving the reduction zone is notsufficient to fully heat the charge, the extra heat may be suppliedelectrically, through electrodes 64, or by using a surplus of fuel inZone I in proportion to the ore being reduced, and burning this excesscarbon monoxide with air injected at the proper place as at 61 in ZoneIII. Alternately, this heat may be supplied by adding another fuel, forexample CH together with the required air at 61. Some solid fuel may beadded with the charge and burned with air supplied at 61. When there isa surplus of heat as sensible heat in the off gases, it may be used forpre-heating air, fuel or for other economic purposes.

Molten slag and molten iron collect at the bottom of the furnace and maybe tapped at 24 and 26, respectively.

FIG. 4 shows a modification for use in cases where greater flexibilityin feed control is desired and where installations are made undercircumstances which permit efiicient use of off gases which are muchhotter than the stack gases in the operation of the furnace of FIG. 1.

The rear portion of the furnace in FIG. 4 is generally similar to thatshown in FIG. 1 except that the wall 20a is longer and includes anupstanding dam 22a extending transversely across the apparatus andprovided at the sides with tap holes 24a, 26a, 28a and 30a for theremoval of slag and reduced metal. The back of the apparatus includesthe refractory wall a of plenum chamber 42a which communicates with thesource of combustion-supporting gas. Baflles 44:: again aid in directingthe combustion-supporting gases into uniform, or otherwise distributed,flow along the height of the wall through spaced apertures 45a.

Arranged over the furnace chamber are a succession of fuel and orefeeds, each provided with a conventional feed mechanism fordistributingthe material in a continuous manner across the width of the furnace. Thefirst feed a again located substantially over the rear portion of thefurnace, is followed in succession by a series of four, in this case,additional feeds so that the particular content and/or rate of feed ofmaterial may differ at the various feeds.

At the far right in FIG. 4 there is a stack 52a for the off gases andprovision is made for the introduction of small amounts of gases such asair, or oxygen if desired, through a series of apertures 54a.

Each of the compartmentalized feeds Nos. 1, 2 and 4 may also be providedwith gas inlets 56a for pre-heating or combustion-supporting purposes.Feeds Nos. 3 and 5 may provide for exhausting gases, principally those,if any, introduced at feeds Nos. 2 and 4, respectively.

In this type of furnace the first feed is again for predominantly solidfuel, with in some cases, some iron ore and bauxite, followed by second,third, fourth and fifth feeds of fuel, ore and limestone in varyingcontents. If the iron ore is reasonably low in silica content (e.g.,unsintered taconite) and has some calcium carbonate and the bauxite hasa high alumina content, a molten calcium aluminate may be tapped at 24aand a high quality ferrosilicon at 26a. Or laterites from Cuba andJamaica may be fed at No. 1 feed to supply iron ore high in alumina.

Here the rear zone beneath the first feed again operates to producereducing gas in the form of carbon monoxide, and is held in position andoverlaid with layers of successive vertical zones of ore, and/ or ore,stone and fuel in varying proportion.

With this form of furnace it is necessary that the reducing zone extendthroughout the entire portion of the charge and hence sufiicientendothermic heat has to be supplied throughout the bed to insure thatthe products of partial combustion do not fall below a temperature ofabout 2700 F. and emerge from the inclined olfgas surf-ace. 60a of thebed at at least that temperature, since otherwise the ore fed at feed 5would not be reduced.

Combustion in the rich fuel zone of the bed adjacent the ingress ofoxygen-enriched air produces a temperature higher than 4000 F. Withpre-heating of the ore charges and combustion of the fuel supplied atthe various feeds,

.5 supported in addition by the oxygen content of the ore, hightemperature conditions can prevail throughout the bed. In addition,secondary air or oxygen may be introduced through air inlets 54a to aidin maintaining the off-gas surface temperature.

Further combustion-supporting gas may be introduced through inletsbetween the feed compartments one of which is shown at 65a, and atinlets 61a through darn 22a if necessary to secure continuous reactionin the portion of the bed to the right of dam 22a.

The number of ore-fuel zones is limited only by the ability to maintaina reducing condition and a high temperature in the zone of eachadditional charge. Accordingly, in certain instances additional heat canbe supplied by electrical input through carbon electrodes or a carbonblock lining. Such electrical energy can, if desired, be readilysupplied from energy recovered from the products of combustion.

As will be seen, in contrast with the burden of a conventional blastfurnace whose vertical dimension must be limited in order to maintainair permeable structure, the weight of the burden in the reductionfurnace shown in FIG. 4 is transverse to the blast flow. The height ofthe furnace may thus remain limited Without restricting the volume ofthe burden. Since, however, in a conventional blast furnace the offgases are at a temperature not substantially higher than 300 F., it willbe seen that the much hotter off gases from the present furnace are acomparably more valuable by-product and therefore must go to heatexchangers (shown at 62a) or find other use in order to provideeconomical operation.

While all the iron from such a bed may be collected through a singletap, it may be desirable and is within the contemplation of theoperation of such a furnace to have multiple taps, as shown in FIG. 4,since often there can be variation in the quality of the iron and of theslag withdrawn from the separate vertical zones of the unitary bed.

The electric power can be supplied to Zone II through electrodes 63a,64a shown in FIGS. 4 and 5, so that the bed is supplied with the heatequivalent to the kilowatts used. Three electrodes can be used withthree-phase alternating current at a suitable voltage.

As shown in FIG. 5, it is contemplated that the bed may have flared sidewalls 66a, 68a in order to accommodate the additional volumes of gasfrom the oxygen, ore and limestone used either for combustion orpreheating purposes.

Because of the entirely horizontal configuration of the bed in FIG. 4requiring the hot off-gas surface 60a in Zone III, fuel is required atthe feeds Nos. 4 and 5 in order to maintain the carbon monoxide contentand temperature high enough to accomplish the FeO to Fe reduction rightup to the off-gas surface. This is in contrast to the furnace of FIG. 1where the carbon monoxide gasore contact is much more counterfiow thanthe transverse flow in FIG. 4 and in other furnaces to be laterdescribed. Accordingly, as can be seen, in the furnace of FIG. 1

CO CO-l-CO by volume content and temperatures above 2200F. can bereadily maintained near the bottom of the ore charge, as is necessary toaccomplish the FeO to Fe reduction. For example, the

CO CO+CO ratio by volume should be about at 2200" F. and at 2700 F. 'orof the order of 72% on a weight or pound mol basis.

However, the reduction of Fe 0 and Fe 0 to FeO take place at much lowercarbon monoxide contents (as little as 20% carbon monoxide in thepresence of 10% H 0 and at temperatures as low as 1200 F.). Thus in theupper part of the furnace of FIG. 1, the lower-carbonmonoxide,lower-temperature reduction can take place.

In FIG. 4, however, if low CO content gas only is present near theoff-gas surface, satisfactory reduction of the Fe O in the ore from feedNo. 5 will not be secured. Hence additional carbon monoxide must begenerated within the bed through the addition of some fuel beyond feedNo. 1.

In the apparatus shown in FIG. 6, Zone III has in effect been omitted,and the feeds are confined to three in number. The dam 22a has beenomitted since the overall thickness of the beds is substantiallydecreased from that shown in FIG. 4, but electrodes 64 are stillprovided and additional electrodes 82 are furnished to providesuflicient heat to insure reducing conditions throughout without thenecessary feed of further solid fuel at feeds Nos, 2 and 3.

In the operation of a furnace as shown in FIG. 6, something like 60% ofthe total available heat may be utilized in ore reduction, leaving about22% available in the off gases for the open-hearth of which about 7% issensible heat and 15% calorific heat developed by burning the CO offgases and H present with additional air or oxygen introduced through theinlets 80 and/or 81.

In this case, as in other cases, some natural gas containing CH as aprincipal constituent may also be introduced as part of the gas flowingthrough the perforate rear wall 40b.

The following tables show illustrative examples of operations of thefurnaces in FIGS. 1, 4 and 6, respectively. Zone II, in the case of FIG.4, is taken as the composite operation of the materials fed at feeds 2and 3 and Zone III is taken as the composite operation of the materialsfed at feeds 4 and 5, whereas in FIG. 6, the materials fed at feeds 2and 3 are taken as being the Zone II operation:

Fig. 1 Fig. 4 Fig. 6

Lb.-m01 Ton Lb.-mo1 Ton Lb.-mol Ton Enteoring Zone I:

ZONE I 51, 066' 170, 000 2, 380 at 280F.

Fig. 1 Fig. 4 Fig. 6

Lb.-rnol Ton Lb.-mol Ton Lb.-mo1 Ton ZONE n Entering Zone II:

21, 000 1, 077 22, 000 1, 760 See materials 31, 000 504 33, 000 528entering Zone 6, 300 315 6, 600 330 III 6, 300 139 6, 600 145 ZONE IllGas leaving Zone II above Molten Fe The relative quantities used asillustrative for a FIG. 4 operation differ somewhat from those given atpage 9 of my earlier co-pending application Serial No. 817,143. Inparticular a calculated electric heat input is now provided for Zone IIto heat the charges at feeds Nos. 2 and 3. Secondly, the oxygen for ZoneIII has been increased from 432 to 496 to burn more carbon monoxide inZone III to carbon dioxide with a decrease of carbon monoxide leavingZone III from 2226 to 2114 and an increase in carbon dioxide emergingfrom Zone III from 1056 to 1463 tons, thus supplying more heat for thecharges entering at feeds Nos. 4 and 5. Lastly, in my prior co-pendingapplication at page 9 the stone fed into Zones II and III was given asof the same Weight as the slag leaving. The above calculations for FIG.4

c-combustion sh-sensible heat ffusion or dissociation k-electric heatHEAT BALANCE (FIG. 1)

are based upon the use of CaC0 in amount equal to 0.3 X the Fe O whilethe slag is calculated as equal to 0.4 X the Fe O to allow for thegangue in the ore, plus 0.02 X the carbon to allow for ash in the fuel.The slag is considered as equivalent to CaOSiO- with a mol weight of116. The present calculations are thus more detailed than those setforth in my prior application to illustrate more exact procedure forattaining adequate temperature in Zones II and III.

Heat balances for the above three tabulated operations are as follows,in which the following symbols are used:

ZONE I 90,000 C+5l,000 Oz+170,000 N;+l,800 Slag=78,000 CO+12,000Cori-170,000 Ng+1,800 Slag Btu. per pound mol -lli (m1 ons DevelopedExtracted 78,000 C+39,000 O =78,000 CO at 47,556 (0) 3, 709 12,000C+12,000 O =l2,000 CO: at 169,290 (0) 2, 032 Heat in 78,000 CO at 2700F. at 21,384 (511).... 1, 1568 Heat in 12,000 CO; at 2700 F. at 33,750(sh) 405 Heat in 170,000 N; at 2700" F. at 21,087 (sh) 3, 585 Heat in1,800 Slag at 2700 F. at 89,000 (sh) 160 Radiation at 5% 306 Preheat221,000 All to 280 F. at 1,750 (Sh) 390 HEAT BALANCEContinued (FIG. 1

ZONE II 78,000 CO+12,000 COg--l170,000 N3+26,0G0 Fe O3=52,000 Fe+00,000COM-170,000 N z (The above reactions take place in two stages) Radiationat 5% Deficiency supplied from Zone 111 Zone 11a26,000 Fe;0z+heat=52,000Fe0+13,000 0 at 124,560 (I) 3, 238 25,000 CO+13,000 Og=26,000 CO at121,734 (0) 3,165 158 Zone Ink-52,000 FeO+l1eat=52,000 Fe+26,000 0 at114,840 (1) 5, 972 52,000 CO+20,000 O =52,000 CO; at 121,734 (0) 6, 230Deficiency supplied from Zone 111 and Radiation at 5% 54 312 ZONE III90,000 C02+110,00o N at 2700 F. to heat charge 0120,000 F0203+(7,800CaCOa)+ 0,400 slag t0 2700 F.

Heat 26,000 F0 03 to 2700 F. at 96,000 (sh) Calcine 7,800 (321003 to C00and CO; at 78,000 (f) Heat 10,400 Slag to 2700 F. at 89,000 (sh)Radiation at 5% Excess in Zone III Heat in 90,000 CO at 2700 F. at33,750 (sh) 3, 038

Heat in 170,000 N; at 2700" F. at 21,300 (sh) ,585

Heat in 97,800 CO; at 300 F. at 2,850 (sh) Heat in 170,000 N; at 300 F.at 2,130 (sh) Net excess after supplying 285 to Zone 11 1, 338

HEAT BALANCE (FIG. 4)

ZONE I 94,000 C+40,000 Uri-4,000 F0203+2,000 CaCO =90,000 (TO-03,000Fe+2,720 Slag Btu. per pound mol (millions) Developed Extracted 4,000 FeO3+heat=8,000 Eel-0,000 0 at 354,240 (f) 94,000 C+47,000 O f 2,000 C200calcined to 2,000 Ca0+2,000 O0 0 2,000 00 decomposed to 2,000 CO+1,000 0at 74,178 (f) Heat in 96,000 CO at 2700" F. at 21,384 (sh) Heat in 8,000Fe at 2700 F. at 31,276 (Sh)-.. Heat in 2,720 Slag at 2700 F. at 39,000(sh) Radiation at 37 ZONE II 03,000 0+21,000 Fe 0a+6,300 00003-10000000:15.0,000 CO+42,000 Bel-6,300 c02+11,100 Slag 21,000 Fe O +heat=2,000Fc+31,500 01 at 354,240 (1) 03,000 c+31,500 0 =03,000 00 at 47,550 (06,300 CaCOa calcined to 6,300 GaO+6,300 CO: at 78,000 (i) Heat 63,000 Cto 2700 F. at 12,720 (sh) Heat 11,160 Slag to 2700 at 89,000 (311)..

Heat 21,000 F0 0 to 2700 F. at 96,000 (sh) Heat 6,300 C0 150 2700 F. at33,750 (sh) 2,770,000 kw. hr. at 3413 Btu. per kw. hr. (1:) Radiation at5% ZONE III 48,000 c+31,000 0,044,000 Fe O +4,200CaCO3+630gO%(1)g-l159,000 CO=28,000 Fe+151,000 c0+00,500 002+ s 14,000Fe O:.+heat=28,000 Fe+21,000 0 at 354,240 (1). 48,000 C-l-48,000 0=48,000 00 at 169,290 (0) 8,000 CO+4,000 O =8,000 CO; at 121,734 (0)4,200 CaCOa calcined to 4,200 Ca0+4,200 00 at 78,000 (I) Heat 48,000 Cto 2700 F. 0.0 12,720 (Sh) Heat 31,000 0 to 2700 F. at 22,275 (sh) Heat14,000 F6203 t0 2700 F. at 96,000 (sh) Heat 6,750 Slag to 2700 F. at89,000 (sh) Radiation at 6% HEAT BALANCE (FIG. 6)

ZONE I 90,000 C+39,000 Owl-4,000 FegO3+1,200 CaCO3=90,000 CO+1,200 CO+8,000 Fe+3,400 Slag 000 Fe Oa+heat=8,000 Fe-l-fi,000 Oz at 354,240 (i)4 90,000 (Li-45,000 O3=90,000 CO at 47,556

1,200 02.00; calcined to 1,200 Ca0+1,200 00-, at 78,000 (i) Heat in90,000 CO at 2700 F. at 21,384 (sh) Heat in 1,200 CO, at 2700 F. at33,750 (sh). Heat in 8,000 Fe at 2700 F. at 31,276 (sh) Heat in 3,400Slag at 2700 F. at 89,000 (sh). Radiation at 5% ZONE II 22,000FegO3+6,600 CaCOa+90,000 CO+l,200 CO3=44,000 Fe+33,000 02+7,800

22,000 Fe 03+heat=44,000 Fe+33,000 0 at 354,240 (1'). 66,000 oo+33,000Oz=66,000 CO at 121,734 (0) 6,600 CaCO calcined to 6,600 Ca0+6,600 CO;at 78,000 (1) Heat 22,000 F0203 to 2700 F. at 96,000 (sh) Heat 8,800Slag to 2700 F. at 89,000 (sh) Electric heat required 1,052,000 kw.-hr.at 3413 B.t.u. (k) Radiation at 3.6%.-

Gas leaving ZONE II:

66,000 CO;+7,800 CO =73,800 CO 90,000 CO66,000 CO=24,000 CO Arrowsutilized in the drawings relate only to the fiow direction of gases, asdistinguished from fuels and liquids. Fuels used may be anthracite,coke, charcoal, dry wood or any free-burning fuel.

Although specific embodiments of the invention have been describedherein, it is not intended to limit the invention solely thereto, but toinclude all of the obvious variations and modifications within thespirit and scope of the appended claims.

What is claimed is:

1. A method for the reduction of iron ore comprising forming in afurnace a unitary porous bed constituted of free-burning solidcarbonaceous fuel, iron ore and limestone in varying proportion acrosssaid bed, the fuel constituting a rear vertically extending zone of saidbed overlaid with successive horizontally spaced vertically extendingzones containing varying contents of ore, said bed having an oif-gassurface extending upwardly from the bottom of said bed horizontallyopposite said rear fuel zone, blowing oxygen-containing gas into therear vertically extending surface of said bed and substantiallyhorizontally through said bed as the materials descend in the furnace toreduce the iron contained in said ore and to drive the gaseous reactionproducts of said carbonaceous fuel out of said off-gas surface at atemperature above the liquid flowing point of the iron in said ore,liquefying the iron in the ore in said bed and the other incombustiblpsin said bed to cause them to flow downwardly in liquid form towards thebottom of said bed and maintaining said bed porous for the continuedhorizontal passage of gas therethrough, collecting the liquefied ironand other liquefied incombustibles as they flow out of the bottom ofsaid bed, and replenishing at least a portion of said bed by feeding amixture of fuel, iron ore and limestone in varying proportions at aplurality of separate horizontally spaced points along the top of thebed laterally in advance of said off-gas surface.

2. A method as claimed in claim 1, wherein fixed sourcs of exothermicheat are provided at horizontally spaced intervals along the sides ofsaid bed to convert carbon dioxide products of reaction to active carbonmonoxide in said bed, the gases issuing from said off-gas surface beingprimarily reducing gas at a temperature exceeding about 2700 F.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCESTieman: Iron and Steel, Third edition, McGraw-Hill Book Co., Inc., NewYork, 1933, pages 161 and 162 relied DAVID L. RECK, Primary Examiner.

MARCUS U. LYONS, RAY K. WINDHAM, ROGER L. CAMPBELL, WINSTON L. DOUGLAS,

Examiners.

1. A METHOD FOR THE REDUCTION OF IRON ORE COMPRISING FORMING IN AFURNACE A UNITARY POROUS BED CONSISTUTED OF FREE-BURINING SOLIDCARBONCEOUS FUEL, IRON ORE AND LIMESTORN IN VARYING PROPORTION ACROSSSAID BED, THE FUEL CONSTITUTING A REAR VERTICALLY EXTENDING ZONE OF SAIDBED OVERLAID WITH SUCCESSIVE HORIZONTALLY SPACED VERTICALLY EXTENDINGZONES CONTAINING VARYING CONTENTS OF ORE, SAID BED HAVING AN OFF-GASSURFACE EXTENDING UPWARDLY FROM THE BOTTOM OF SAID BED HORIZONTALLYOPPOSITE SAID REAR FUEL ZONE, BLOWING OXYGEN-CONTAINING GAS INTO THEREAR VERTICALLY EXTENDING SURFACE OF SAID BED AND SUBSTANTIALLYHORIZONTALLY THROUGH SAID BED AS THE MATERIALS DESCEND IN THE FURNACE TOREDUCE THE IRON CONTAINED IN SAID ORE AND TO DRIVE THE GASEOUS REACTIONPRODUCTS OF SAID CARBONACEOUS FUEL OUT OF SAID OFF-GAS SURFACE AT ATEMPERATURE ABOVE THE LIQUID FLOWING POINT OF THE IRON IN SAID ORE,LIQUEFYING THE IRON IN THE ORE IN SAID BED AND THE OTHER INCOMBUSTIBLESIN SAID BED TO CAUSE THEM TO FLOW DOWNWARDLY IN LIQUID FORM TOWARDS THEBOTTOM OF SAID BED AND MAINTAINING SAID BED POROUS FOR THE CONTINUEDHORIZONTAL PASSAGE OF GAS THERETHROUGH, COLLECTING THE LIQUEFIED IRONAND OTHER LIQUEFIED INCOMBUSTIBLES AS THEY FLOW OUT OF THE BOTTOM OFSAID BED, AND REPLENISHING AST LEAST A PORTION OF SAID BED BY FEEDING AMIXTURE OF FUEL, IRON ORE AND LIMESTONE IN VARYING PROPORTIONS AT APLURALITY OF SEPARATE HORIZONTALLY SPACED POINTS ALONG THE TOP OF THEBED LATERALLY IN ADVANCE OF SAID OFF-GAS SURFACE.